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1.
含聚二甲基硅氧烷的聚醚聚氨酯膜透气性及表面性质研究 总被引:2,自引:0,他引:2
以聚二甲基硅氧烷(PDMS)/聚四氢呋喃(PTMO)为软段,4,4'-二环己基甲烷二异氰酸酯(HMDI)为硬段(丁二醇BD为扩链剂)制成的多相嵌段共聚物作为基质材料,进行了气体(O2和N2)透过性试验,同时对膜材料进行了ESCA表面分析。结果表明,共聚物膜的透气性能取决于材料中连续相组分,随着软段中PDMS含量的改变而变化。当PDMS含量较高时,共聚物膜显示出PDMS均聚物的特性,具有较高的气体秀 相似文献
2.
This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from 13C MAS‐NMR and 29Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
Monolayer vanadium species are mainly in the V(V) valence state, but with XPS a small fraction of V4+ species are identified. Prolonged analysis treatment increases the V4+ concentration. With increasing vanadium concentration, a monolayer coverage corresponding to 1 mg V2O5 per m2 develops, and it contains additional layers with a thickness of about 250 Å at 4 mg V2O5 per m2, covering 3% of its surface area. 相似文献
4.
Yan Song Wenming Qiao Seong‐Ho Yoon Isao Mochida Quangui Guo Lang Liu 《应用聚合物科学杂志》2007,106(4):2151-2157
Adsorption of low concentration formaldehyde on pitch‐based, rayon‐based, and PAN‐based activated carbon fibers (ACFs) and an unactivated PAN‐based carbon fiber (PAN‐CF) was investigated by a dynamic method. The pore structure and surface chemistry of these samples were characterized by liquid nitrogen adsorption, elemental analysis, and X‐ray photoelectron spectroscopy. Results revealed that the pore structure, especially surface chemical composition, greatly influence the formaldehyde adsorption. PAN‐based ACFs showed the highest formaldehyde adsorption capacity because there are more abundant nitrogen‐containing groups, especially pyrrolic, pyridonic, pyridinic, and quaternary on the surface. The breakthrough time and formaldehyde adsorption capacity of one kind of PAN‐ACF were 361 min and 0.478 mmol/g, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
5.
6.
NOTE The Application of Surface Analysis Techniques in the Adhesive Bonding of Oily Automotive Steel
There are fewer papers on the adhesive bonding of steel for structural applications than for aluminum and titanium alloys. However, the approach to the adhesive bonding of all three adherends has been similar, that is, the surfaces are pretreated prior to bonding. Trawinski, et al.1,2,3 reviewed several conversion coatings or etching processes used for steel. Haak and Smith4 selected two surface treatments among nineteen based on minimal cost, simplicity and good durability. Smith5 has reported work on stainless steel-epoxy bonds under hydrothermal stress. Bischof, et al.6 investigated the effect of surface pretreatment of steel on bonding strength obtained with polyvinyl chloride. Ziane, et al.7 identified four fracture zones resulting from shear loading of epoxy bonded galvanized steel following four different surface pretreatments. But in some cases, as in the automotive industry, there is a need to bond oily steel directly without surface pretreatment. Rosty, et al.8 have reported a study of the role of fillers and cure temperature on the shear strength of oily steel bonded with epoxy. None of the reported research utilizes both microscopic and spectroscopic techniques to analyze the fracture surfaces. 相似文献
7.
Of the several techniques available for the surface modification, plasma processing has proved to be very appropriate. The low temperature plasma is a soft radiation source and it affects the material only over a few hundred Å deep, the bulk properties remaining unaffected. Plasma surface treatment also offers the advantage of greater chemical flexibility. PET films are widely used for packaging and electrical insulation. The studies of adhesion and printability properties are important. In the present study PET films are treated in air plasma for different time of treatment. The improvement in adhesion is studied by measuring T-peel and Lap shear strength. In addition, printability of plasma treated PET films is studied by cross test method. It has been found that printability increases considerably for plasma treatment of short duration. Therefore it is interesting to study the surface composition and morphology by contact angle measurement, ESCA and AFM. Surface energy and surface roughness can be directly correlated to the improvement in above-mentioned surface related properties. It has been found that the surface oxidation occurs containing polar functional groups such as C-O, COO. A correlation of all such observations from different techniques gives a comprehensive picture of the structure and surface composition of plasma treated PET films. 相似文献
8.
《Journal of Adhesion Science and Technology》2013,27(1):817-827
Polyolefin films were surface-modified by different methods to improve the wetting and adhesion of water-borne printing inks. Polyethylene (PE) films were treated with corona at various energy levels. Surface-modified PE films were characterized by contact angle measurements and electron spectroscopy for chemical analysis (ESCA). Good wetting was already achieved with treatment at a lower energy level. Various degrees of adhesion were obtained at various degrees of treatment. A hydrophilic monomer, 2-hydroxyethylmethacrylate (HEMA), was polymerized onto the surfaces of polypropylene (PP) with radiation-induced grafting, which was carried out at two different radiation doses. In both cases, a thick, visible layer of polyHEMA was formed on the surface of PP, and satisfactory wetting was already achieved at lower radiation doses. Scanning electron microscopy (SEM) showed that different degrees of roughness were achieved at various radiation doses. Like the case of corona-treated PE, different degrees of adhesion were obtained at different degrees of surface treatment. This study shows that improved wetting alone is not satisfactory for good practical adhesion', regardless of the surface modification method used. 相似文献
9.
The surface properties of two perfluoroalkylethyl acrylic copolymers—aqueous, Zonyl®329 and solvent‐based, Zonyl®225—were studied. Zonyl®329 is a water‐based dispersion and Zonyl®225 a solvent‐based copolymer solution; both polymers have the same perfluoroalkyethyl side chains [F(CF2)nCH2CH2? ] but have different comonomer compositions. Thin films, prepared by dip coating onto mica and quartz, with and without annealing, were characterized by contact angle and by X‐ray photoelectron spectroscopy (XPS). The contact angle measurements showed little variation with polymer and with substrate, consistent with the supposition that the perfluoroalkylethyl chains aggregate on the surface and thus dominate surface properties, irrespective of the composition of the rest of the polymer. XPS revealed only small variations in surface chemistry for studied films. Annealed films showed improved segregation for solvent‐based Zonyl®225, which has both hydrocarbon alkyl and perfluoroalkylethyl side chains; the presence of hydrocarbon alkyl chains enables the perfluoroalkylethyl chains to reorganize after annealing. Depending on the external conditions, this thermal treatment can enable more perfluoroalkylethyl chains to reach the film surface (solid/air interface), leading to a reduction in the dispersive‐dominant surface and enhancement in perfluoroalkylethyl segregation. This suggested that perfluoroalkylethyl side chains dominate the surface properties, which are thus not dependent on substrate, backbone composition, or formulation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
10.
根据红外分析、顺磁共振、光电子能谱及化学分析结果,我们提出了氟塑料—46的辐射交联反应机理。交联点不一定如Bowers等由理论分析推断的在氟塑料—46的—CF_3侧链上。我们认为可以由 CF_3链侧自由基如—CF_2—CF—CF_2—,—CF_2—C—CF_2—,直接复合成交联键,H型交联;或由链侧自由基和链端自由基复合通过支化而交联,即T型或Y型交联。后者机率更多些。 相似文献